Everyone on this list receives reminder emails: once at the start of the week listing appointments, and again the day before & on the day.
To send reminders automatically, add a cron job in Hostinger hPanel:
hPanel → Advanced → Cron Jobs → Add New Cron Job
Set the schedule to 0 8 * * * (runs at 8am every day) and the command to:
php /home/u468815076/domains/tutorcentral.co.uk/public_html/mum/reminders_cron.php
The script automatically sends: a weekly digest every Monday, a day-before reminder, and a morning-of reminder.